Formation of through via before contact processing

ABSTRACT

The formation of through silicon vias (TSVs) in an integrated circuit (IC) die or wafer is described in which the TSV is formed in the integration process prior to contact or metallization processing. Contacts and bonding pads may then be fabricated after the TSVs are already in place, which allows the TSV to be more dense and allows more freedom in the overall TSV design. By providing a denser connection between TSVs and bonding pads, individual wafers and dies may be bonded directly at the bonding pads. The conductive bonding material, thus, maintains an electrical connection to the TSVs and other IC components through the bonding pads.

This application is a continuation of U.S. patent application Ser. No.13/074,883, filed Mar. 29, 2011, and entitled “Formation of Through ViaBefore Contact Processing,” which is a continuation of U.S. patentapplication Ser. No. 11/769,559, filed Jun. 27, 2007, and entitled“Formation of Through Via Before Contact Processing,” now U.S. Pat. No.7,939,941, which applications are hereby incorporated herein byreference.

TECHNICAL FIELD

The present invention relates generally to integrated circuitfabrication, and more particularly to forming a through via beforecontact processes.

BACKGROUND

Generally, the speed at which an integrated circuit operates isinfluenced by the distance between the farthest separated componentsthat communicate with each other on the chip. Laying out circuits asthree-dimensional structures has been shown to significantly reduce thecommunication path length between on-chip components, provided thevertical distances between the layers are much smaller than the chipwidth of the individual layers. Thus, by stacking circuit layersvertically, the overall chip speed is typically increased. One methodthat has been used to implement such stacking is through wafer bonding.

Wafer bonding is the joining together of two or more semiconductorwafers on which integrated circuitry has been formed. Wafers aretypically joined by direct bonding of external oxide layers or by addingadhesives to inter-level dielectric (ILD) layers. The bonded resultproduces a three-dimensional wafer stack which is subsequently dicedinto separate “stacked die,” with each individual stacked die havingmultiple layers of integrated circuitry. In addition to the increasedspeed that the three-dimensional circuitry typically experiences, waferstacking offers other potential benefits, including improved formfactors, lower costs, and greater integration through system on chip(SOC) solutions. In order to enable the various components integratedwithin each stacked die, electrical connections are provided thatprovide conductors between vertical layers. Through silicon vias (TSVs)are typically fabricated to provide vias filled with a conductingmaterial that pass completely through the layer to contact and connectwith the other TSVs and conductors of the bonded layers.

In general, TSVs are formed after the contact process or even after thetop metallization process. Examples of such post-process methods aredescribed in U.S. Pat. No. 6,642,081 to Patti (hereinafter Patti) andU.S. Pat. No. 6,897,125 to Morrow, et al., (hereinafter Morrow). Pattidescribes forming the TSV after the top metallization, while Morrowdescribes TSV formation after formation of the first contact orinterconnect structure. One disadvantage of forming TSVs after thecontact or metallization process is that the density of the via istypically less because of etch and design limitations. Etching throughmetallization layers does not typically result in a recess that wouldallow for a particularly dense TSV. Moreover, again because the processetches through metallization and contact regions, the design of the viais limited based on the existing structures of the metallization layersand contact regions. Thus, designers will typically have to design theTSV network around the existing metal layers and contact traces. Thislimited design and density potentially creates connection, contact, andreliability problems.

An additional limitation to current TSV systems and methods is thelimited availability for thermal dissipation. For example, Morrow andPatti disclose TSV processes, where the TSVs are formed after contact ormetallization processing. Therefore, should there be a desire to designTSVs for thermal dissipation, those TSVs will typically occupy the areafor normal design, since the contact and metallization layers arealready in place.

SUMMARY OF THE INVENTION

These and other problems are generally solved or circumvented, andtechnical advantages are generally achieved, by preferred embodiments ofthe present invention which provide for the formation of through vias(TVs), such as through silicon vias (TSVs), in an integrated circuit(IC) die or wafer prior to contact or metallization processing. Contactsand bonding pads may then be fabricated after the TSVs are already inplace, which enables individual wafers and dies to be bonded in stacksfrom the bonding pads. The bonding material provides complete electricalconnection to the TSVs through the bonding pads.

In accordance with a preferred embodiment of the present invention, amethod for forming one or more TVs includes forming one or more recessesin a first wafer prior to depositing an interlayer dielectric (ILD)layer. The recesses extend from a front-side surface of the first waferto a predetermined distance from a back-side surface of the wafer.Conductive material is then deposited into the recesses to form the TV.

In accordance with a preferred embodiment of the present invention, astacked IC includes a first component located on a first semiconductordie and one or more additional components located on one or moreadditional dies. The first semiconductor die and the one or moreadditional dies are vertically attached by a bonding medium, while thefirst component and the one or more additional components areelectrically connected. There is at least one TSV located in at leastone of the first semiconductor die and additional dies, where the TSV isformed prior to forming contacts for the stacked IC.

In accordance with another preferred embodiment of the presentinvention, a semiconductor component includes at least one wafer havinga TV formed prior to deposition of a contact dielectric layer.

In accordance with another preferred embodiment of the presentinvention, a semiconductor component includes one or more dies eachhaving one or more devices integrated therein. There is also at leastone TSV, which is formed prior to creation of any contacts. Thefront-end of the TSV is electrically connected to contacts on thefront-side of the TSV's corresponding die. The back-end of the TSV isexposed and available for providing electrical conduction after removinga portion of the substrate on the back-side of the corresponding die.

In accordance with another preferred embodiment of the presentinvention, a method for bonding one or more wafers includes positioninga first wafer, which has one or more bonding pads connected to at leastone TV that provides an electrical connection to one or more componentson the first wafer. A second wafer is positioned in relation to thefirst wafer. The second wafer also has one or more bonding padsconnected to at least one TV that provides the electrical connection toone or more components on the second wafer. The bonding pads of thefirst and second wafers are bonded together using a material that iselectrically compatible, such that electricity may be conducted betweenthe bonding pads of the first and second wafers when the bonding iscomplete.

In accordance with another preferred embodiment of the presentinvention, a method includes forming at least one TSV in a first IC die.After the TSV is formed, the first IC die is processed adding one ormore contacts and one or more bonding pads. At least one additional TSVis formed in an additional IC die, after which the additional IC die isprocessed to also add one or more contacts and one or more bonding pads.The bonding pads of the two IC die are joined using a rigid conductingmaterial.

In accordance with another embodiment a method for forming one or morethrough vias comprises forming active devices on a front-side of a firstwafer, the first wafer comprising a back-side opposite the front-side ofthe first wafer. One or more recesses are formed in the first waferprior to forming an interlayer dielectric (ILD) layer over thefront-side of the first wafer, the one or more recesses extending fromthe front-side of the first wafer to a predetermined distance from theback-side of the first wafer. Conductive material is formed in the oneor more recesses, the conducting material forming one or more throughvias. A metallization layer is formed over the back-side of the firstwafer, the metallization layer comprising a first contact electricallyconnected to at least one of the one or more through vias and also beingexposed to allow current to flow to at least one of the one or morethrough vias.

In accordance with another embodiment a method for bonding one or morewafers comprises positioning a first wafer, the first wafer havingactive devices and a first bonding pad connected to a first throughsilicon via (TSV), the first TSV extending through an internal portionof the first wafer. A second wafer is positioned in relation to thefirst wafer, the second wafer having a second bonding pad connected to asecond TSV, the second TSV extending through the second wafer. The firstbonding pad and the second bonding pad are bonded using a material thatis electrically compatible with the first bonding pad and the secondbonding pad. A third bonding pad is formed on a back-side of the firstwafer, the third bonding pad connected to the first TSV.

In accordance with another embodiment a method for forming semiconductordevices comprises forming a first through silicon via (TSV) in a firstintegrated circuit (IC) die, the first IC die comprising active deviceslocated on a front-side. After the forming the first TSV, the first ICdie is processed to add a first contact connected to the first TSV and afirst bonding pad connected to the first contact. A second TSV is formedin a second IC die. After forming the second TSV, the second IC die isprocessed to add a second contact connected to the second TSV and asecond bonding pad connected to the second contact. The first bondingpad is bonded to the second bonding pad using a rigid conductingmaterial.

An advantage of a preferred embodiment of the present invention is thatTSV density can be increased for three-dimensional integrated circuitswhen formed prior to the contact and metallization processing. A denserTSV provides a better and more reliable connection to the underlyingdevices and components.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIGS. 1A-1M are cross-sectional views of a wafer having a TSV formedaccording to one embodiment of the present invention;

FIG. 2 is a cross-sectional view of a wafer having through vias formedin the substrate and dielectric layers according to one embodiment ofthe present invention;

FIG. 3 is a cross-sectional view of a wafer having vias formed in thesubstrate and TSV dielectric layer according to one embodiment of thepresent invention;

FIG. 4 is a cross-sectional view of a wafer having vias formed in thesubstrate and TSV dielectric layer according to one embodiment of thepresent invention;

FIG. 5A is a cross-sectional view of a wafer having vias formed in thesubstrate and dielectric layer according to one embodiment of thepresent invention;

FIG. 5B is a cross-sectional view of a wafer having vias formedaccording to one embodiment of the present invention;

FIG. 6A is a cross-sectional view illustrating a stacked wafer;

FIG. 6B is cross-sectional view illustrating another stacked wafer;

FIG. 6C is a cross-sectional view illustrating a stacked wafer that hasbeen bonded according to one embodiment of the present invention;

FIG. 7 is a flowchart illustrating example steps executed to implementone embodiment of the present invention;

FIG. 8 is a flowchart illustrating example steps executed to implementone embodiment of the present invention;

FIG. 9 is a flowchart illustrating example steps executed to implementone embodiment of the present invention;

FIG. 10 is a flowchart illustrating example steps executed to implementone embodiment of the present invention; and

FIG. 11 is a flowchart illustrating example steps executed to implementone embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the presently preferred embodiments arediscussed in detail below. It should be appreciated, however, that thepresent invention provides many applicable inventive concepts that canbe embodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

With reference now to FIG. 1A, there is shown a cross-sectional diagramof wafer 10. Wafer 10 comprises substrate 100, which is typicallysilicon (Si), but may also be made of gallium arsenide (GaAs), galliumarsenide-phosphide (GaAsP), indium phosphide (InP), gallium aluminumarsenic (GaAlAs), indium gallium phosphide (InGaP), and the like, andillustrates device 101 processed from substrate 100. In FIG. 1B,insulating layer 102 is deposited on substrate 100 of wafer 10. Oneexample of such insulating material that may be used is phosphosilicateglass (PSG). Etching is performed on wafer 10 to create via recesses 103and 104, as shown in FIG. 1C. In order to prevent any conductingmaterial from leaching into any active portions of the circuitry ofwafer 10, liner oxide 105, such as silicon nitride, is deposited in alayer over wafer 10, including via recesses 103 and 104.

A layer of conducting material, conductor 106, is deposited onto wafer10, as shown in FIG. 1D. Conducting material may comprise variousmaterials, such as copper, tungsten, aluminum, gold, silver, and thelike. Conductor 106 fills via recesses 103 and 104. After removing theexcess portions of conductor 106, either through etching, chemicalmechanical polishing (CMP), or the like, wafer 10 now comprises vias 107and 108 deposited in substrate 100 and insulating layer 102, as shown inFIG. 1E. Additional insulating layer 109 is added on top of insulatinglayer 102 to form combined insulating layer 110, as illustrated in FIG.1F, resulting in vias 107 and 108 being enclosed within wafer 10.

Another set of etching processes creates recesses 111-113, as shown inFIG. 1G, that provide contact to device 101 and vias 107 and 108,respectively through combined insulating layer 110. FIG. 1H illustrateswafer 10 in cross-section after conducting material is deposited ontowafer 10 filling in recesses 111-113 (FIG. 1G). Portions of thisconducting material is then removed through a process, such as CMP, tocreate contact pad 114, contact pad 115, and connector 118, providingcontact to device 101.

It should be noted that an interface exists between contact pads 114 and115 and vias 107 and 108. This interface may comprise a directconnection, as illustrated in FIG. 1H, but may also comprise an indirectconnection, such as through interface 308 (FIG. 3). The variousembodiments of the present invention are not limited to only directconnection interfaces between contacts and vias.

Bonding contacts 120 and 121, as shown in FIG. 1I, are formed bydepositing intermetal dielectric (IMD) layer 119, which insulates device101 from any other circuitry or devices in any wafers bonded to wafer10. Recesses are etched into IMD layer 119 into which conductingmaterial is deposited to form bonding contacts 120 and 121. Theinsulation or dielectric material making up IMD layer 119 is removed oretched to reveal bonding contacts 120 and 121 slightly elevated abovethe top of IMD layer 119.

It should be noted that the bonding contacts 120 and 121 are not limitedto the positions in relation to contact pads 114 and 115, as illustratedin FIG. 1I. However, a connection between bonding contacts 120 and 121to contact pads 114 and 115 should exist in some manner, such as aredirection layer, conducting traces, or the like.

FIG. 1J illustrates the cross-section of wafer 10 stacked and bonded towafer 11. Wafer 11 comprises substrate 125, insulating layer 124, andIMD layer 126. Each of wafer 10 and 11 include an intermetal dielectriclayer, IMDs 119 and 126 respectively, to limit interference between thevarious components on either wafer. Wafers 10 and 11 are bonded togetherat bonding pads 120-121 and 122-123 to form stacked wafer 12.

It should be noted that any number of different devices, components,connectors, and the like may be integrated into wafers 10 and 11. Thespecific devices or lack of devices that may be illustrated herein arenot intended to limit the embodiments of the present invention in anyway.

FIG. 1K is a cross-sectional view of stacked wafer 12 configuredaccording to one embodiment of the present invention. In order toprovide back-side contact points for vias 107 and 108, portions ofsubstrate 100 are removed, through a process, such as etching, CMP, orthe like, to reveal contact points with vias 107 and 108. In removingsuch portions of substrate 100, vias 107 and 108 slightly protrude fromsubstrate 100. Metallization insulator layer 127 is deposited ontostacked die 12 over the protruding edges of vias 107 and 108, as shownin FIG. 1L. Metallization insulator layer 127 comprises layers ofinsulating material with a layer of liner material to prevent any metalsdeposited in the metallization process from leaching into stacked wafer12. Recesses 130 and 131 are then etched from metallization insulatorlayer 127. The metallization process results in the formation of contactpads 132 and 133, as shown in FIG. 1M. A metal, such as copper,tungsten, aluminum, or the like, is deposited over metallizationinsulation layer 127 and then etched or removed until wafer 12 appearsas illustrated in FIG. 1M. Thus, vias 107 and 108 have been fully formedprior to metallization and the formation of contact pads 132 and 133.

It should be noted that only a limited number of active devices, such asdevice 101, and vias, such as vias 107 and 108, are shown for the easeof illustration and clarity. However, those of ordinary skill in the artwill appreciate that, in practice, the integrated circuitry associatedwith integrated circuits and stacked die may include millions or eventens of millions or more active devices and, further, that interconnectstructures may include tens or even hundreds of conductors in theuppermost ILD layers. Similarly, those of ordinary skill in the art willappreciate that each stacked die will, in practice, include dozens ofback-side connections using conductive vias and leads.

FIG. 2 is a cross-sectional view of wafer 20 having vias 202 and 203formed in substrate 200 and dielectric layer 201 according to oneembodiment of the present invention. Wafer 20 is an exampleimplementation of vias 202 and 203 having contact sets 204 and 205 whichare both smaller than the width of vias 202 and 203 and provide multipleelectrical access points to vias 202 and 203.

FIG. 3 is a cross-sectional view of wafer 30 having vias 304 and 305formed in substrate 300 and TSV dielectric layer 301 according to oneembodiment of the present invention. Wafer 30 is an exampleimplementation of vias 304 and 305 having an interface, interface 308,between itself and contacts 306 and 307. In the illustrated embodiment,contacts 306 and 307 are not in alignment with vias 304 and 305.Interface 308 provides the electrical connection between contacts 306and 307 and vias 304 and 305. Wafer 30 also includes dielectric layer302 between TSV dielectric layer 301 and contact dielectric layer 303.

FIG. 4 is a cross-sectional view of wafer 40 having vias 404 and 405formed in substrate 400 and TSV dielectric layer 403 according to oneembodiment of the present invention. Wafer 40 is an exampleimplementation of vias 404 and 405 having contacts 406 and 407 which arethe same width as vias 404 and 405 and which include dielectric layer402 between TSV dielectric layer 403 and contact dielectric layer 401.

It should be noted that additional and/or alternative embodiments of thepresent invention may leave dielectric layer 402 out of the structure ofa wafer, such as wafer 40.

FIG. 5A is a cross-sectional view of wafer 50 having vias 504 and 505formed in substrate 500 and dielectric layer 501 according to oneembodiment of the present invention. Wafer 50 is an exampleimplementation of vias 504 and 505 including both front-side andback-side contacts through wafer interconnect structures. The exampleembodiment of wafer 50 depicted in FIG. 5A provides back-sidemetallization through bonding pads 506 and 507. Here, back-sideinsulating layer 502, which includes at least one insulating oxide layerand an etch stop or barrier layer, has been thinned to expose bondingpads 506 and 507 in a slight protrusion above back-side insulating layer502. The front-side of wafer 50 also includes metallized bonding pads508 and 509 formed in oxide layer 503 connected to contacts 510 and 511.

FIG. 5B is a cross-sectional view of wafer 50 having vias 504 and 505formed according to one embodiment of the present invention. In theembodiment of wafer 50 depicted in FIG. 5B, insulating layer 502 isflush with bonding pads 506 and 507 on the back-side, while oxide layer503 has been thinned to expose metallized bonding pads 508 and 509,which protrude slightly from oxide layer 503.

It should be noted that each of the example wafers described andillustrated in FIGS. 2-5 are meant to provide alternativeimplementations of vias, contact pads, and bonding pads that may be usedwith various embodiments of the present invention. In additional and/oralternative embodiments of the present invention, any combination of theillustrated options may be used. The illustrated embodiments are notintended to limit the implementation of the various additional and/oralternative embodiments of the present invention.

It should further be noted that the different layers described in theillustrated embodiments may comprise various different materialsdepending on the desired function or availability that the manufacturerdetermines. The metals used for the metallized bonding pads may be anysuitable metal or alloy, such as copper, tungsten, aluminum,aluminum-copper, and the like. Moreover, depending on the desired use orfunction of the different dielectric or insulating layers, any suchdielectric material may be used, such as silicon dioxide, siliconnitride, silicon carbide, silicon oxynitride, and the like. The presentinvention is not limited to use with only a certain limited number ofcompounds and materials.

It should further be noted that the different layers and recesses in theillustrated embodiments may be deposited or created using any number ofa variety of known processes. For example, creation of the variouslayers of oxides, dielectrics, or other layers may be accomplishedthrough chemical vapor deposition (CVD), atomic layer deposition (ALD),or the like. Moreover, removing material from the wafer may beaccomplished through dry or wet etching, chemical mechanical polishingCMP), or the like. The present invention is not limited to any singlesuch method.

When compared to existing methods for forming TSV in semiconductordevices, the TSV formed according to the various embodiments of thepresent invention results in structurally different vias. For example,with current methods that form the TSV after metallization layers, thelocation or placement of the bonding pads will correspond to thelocation of the TSV. There is no additional conductor routing availablethat can electrically connect the TSV to a bonding pad at a differentlocation. In the present application, as illustrated in FIGS. 1H andelement 803 of FIG. 8, contacts are formed in an ILD after the TSVs havebeen formed through the substrate. Therefore, the bonding pads may beplaced in any desired configuration and have electrical connectionsthrough the contacts in the ILD layers to selected TSVs. This novelstructure allows more flexibility in the semiconductor device design.For example, forming a TSV prior to any ILD layers allows for thedesigner to provide for a TSV directed to thermal dissipation withoutsacrificing design space left after the ILD and IMD layers have alreadybeen formed.

Because the existing methods for creating TSVs occurs after the contactor metallization processes, individual wafers are typically joinedeither through direct bonding of oxide layers or through an adhesiveapplied to ILD layers. Once bonded through these methods, the TSVs areformed to provide the electrical connections between wafer layers. Forexample, FIG. 6A is a cross-sectional view illustrating stacked wafer60. Wafer 600 includes, at least, devices 602 and 603 integratedthereon. Wafer 601 includes, at least, device 604. When wafers 600 and601 are joined into a stacked configuration, the oxide layers of wafers600 and 601 are directly bonded. Then, using one of the existingmethods, the TSV are formed after the bonding in order to effect theelectrical connections between devices 602-604 on wafers 600 and 601.

FIG. 6B is a cross-sectional view illustrating stacked wafer 61. Wafer605 includes, at least, devices 609 and 610. Adhesive layer 606 has beenadded to the ILD layer of wafer 605 to facilitate bonding to wafer 608.Wafer 608, in turn, includes, at least, device 611, and has also beenmodified with adhesive layer 607. Wafers 605 and 608 are joined bypressing each other together to initiate contact between adhesive layers606 and 607. After this bonding process, TSVs would then be manufacturedin order to supply the electrical connections between devices 609-611 ofthe newly formed stacked wafer 61.

FIG. 6C is a cross-sectional view illustrating stacked wafer 62 that hasbeen bonded according to one embodiment of the present invention. Wafer612 includes, at least, bonding pad 613, which was formed, at least ingeneral, according to the process described in FIGS. 1A-1M. As such,bonding pad 613 forms an electrical connection with contact 614, whichprovides electrical connection to device 615. Wafer 616 also includes,at least, bonding pad 617, contact 618, and device 619, which were alsoformed, at least in general, according to the process described in FIGS.1A-1M. Wafers 612 and 616 are joined into stacked wafer 62 by directlybonding bonding pads 613 and 617 together. When bonding pads 613 and 617are metal, the bonding may be beneficially implemented using acompatible metal, thus, creating a strong physical bond as well as asecure and definite electrical connection. Thus, wafers 612 and 616 areconnected with a strong physical and electrical bond.

It should be noted that any of several different conductive materialsmay be used to create the bonding pads in the various additional and/oralternative embodiments of the present invention to create the bondbetween those bonding pads. For example, the bonding material may becopper, tungsten, copper-tin alloy, gold-tin alloy, indium-gold alloy,lead-tin alloy, or the like. The present invention is not intended to belimited to any one or a simple set of such conductive materials.

FIG. 7 is a flowchart illustrating example steps executed to implementone embodiment of the present invention. In step 700, one or morerecesses are formed in a first wafer prior to depositing an interlayerdielectric (ILD) layer. The recesses extend from a front-side surface ofthe wafer to a predetermined distance from a back-side surface of thewafer. Conductive material, such as copper, tungsten, aluminum, or thelike, is deposited into the recesses, in step 701, the conductivematerial forming the through vias. The ILD layer is deposited, in step702, on the front-side surface over the through vias, where the ILDlayer is made from a material such as silicon dioxide, silicon nitride,silicon carbide, silicon oxynitride, or the like. In step 703, one ormore contacts are formed in the ILD layer, where selected ones of thecontacts have an electrical connection to selected ones of the throughvias.

FIG. 8 is a flowchart illustrating example steps executed to implementone embodiment of the present invention. In step 800, one or morerecesses are formed in a first wafer prior to depositing an interlayerdielectric (ILD) layer. The recesses extend from a front-side surface ofthe wafer to a predetermined distance from a back-side surface of thewafer. Conductive material, such as copper, tungsten, aluminum, or thelike, is deposited, in step 801, into the recesses, the conductivematerial forming the through vias. In step 802, the ILD layer isdeposited on the front-side surface over the through vias, where the ILDlayer is made from a material such as silicon dioxide, silicon nitride,silicon carbide, silicon oxynitride, or the like. One or more contactsare formed, in step 803, in the ILD layer, where selected ones of thecontacts have an electrical connection to selected ones of the throughvias. An intermetal dielectric (IMD) layer is deposited, in step 804,over the ILD layer and contacts. In step 805, one or more bonding padsare formed in the IMD layer, where the bonding pads have an electricalconnection to the one or more contacts. The bonding pads are alignedwith one or more bonding surfaces on the second wafer in step 806. Instep 807, a bonding medium, such as copper, tungsten, a copper-tinalloy, a gold-tin alloy, an indium-gold alloy, a lead-tin alloy, or thelike, is applied between the bonding pads and the bonding surfaces.

FIG. 9 is a flowchart illustrating example steps executed to implementone embodiment of the present invention. In step 900, one or morerecesses are formed in a first wafer prior to depositing an interlayerdielectric (ILD) layer. The recesses extend from a front-side surface ofthe wafer to a predetermined distance from a back-side surface of thewafer. Conductive material, such as copper, tungsten, aluminum, or thelike, is deposited into the recesses, in step 901, the conductivematerial forming the through vias. In step 902, the ILD layer isdeposited on the front-side surface over the through vias, where the ILDlayer is made from a material such as silicon dioxide, silicon nitride,silicon carbide, silicon oxynitride, or the like. One or more contactsare formed in the ILD layer, in step 903, where selected ones of thecontacts have an electrical connection to selected ones of the throughvias. The through vias are exposed on the back-side of the first wafer,in step 904, by removing an amount of substrate material from theback-side of the first wafer. In step 905, a determination is madewhether it is desired for the exposed back-side via to protrude from thewafer. If not, then an amount equivalent to the predetermined distanceis removed in step 909. Otherwise, an amount greater than thepredetermined distance is removed, in step 907, to achieve the desiredprotrusion.

FIG. 10 is a flowchart illustrating example steps executed to implementone embodiment of the present invention. In step 1000, a first wafer,which has one or more bonding pads connected to at least one throughsilicon via (TSV) that provides an electrical connection to one or morecomponents on the first wafer, is positioned. A second wafer ispositioned, in step 1001, in relation to the first wafer, the secondwafer having one or more bonding pads connected to at least one TSV thatprovides the electrical connection to one or more components on thesecond wafer. The bonding pads of the first and second wafers arebonded, in step 1002, using a material, such as copper, tungsten, gold,copper-tin alloy, gold-tin alloy, indium-gold alloy, lead-tin alloy, orthe like, that is electrically compatible with the bonding pads.

FIG. 11 is a flowchart illustrating example steps executed to implementone embodiment of the present invention. In step 1100, a first waferwhich has one or more bonding pads connected to at least one TSV thatprovides an electrical connection to one or more components on the firstwafer is positioned. A second wafer is positioned, in step 1101, inrelation to the first wafer, the second wafer having one or more bondingpads connected to at least one TSV that provides the electricalconnection to one or more components on the second wafer. The bondingpads of the first and second wafers are bonded, in step 1102, using amaterial, such as copper, tungsten, gold, copper-tin alloy, gold-tinalloy, indium-gold alloy, lead-tin alloy, or the like, that iselectrically compatible with the bonding pads. A portion of thesubstrate material on the back-side of the first wafer is removed, instep 1103, to expose a back-side connection to the TSV. One or moreback-side bonding pads are created, in step 1104, that are electricallyconnected to the exposed back-side connection. The back-side bondingpads of the first wafer are bonded with the bonding pads of anadditional wafer, in step 1105, using the material.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

What is claimed is:
 1. A stacked integrated circuit (IC) comprising: afirst semiconductor die having a front-side and a back-side, whereinsaid first semiconductor die contains a substrate and one or more activedevices on the substrate; one or more through silicon vias (TSVs)running through the substrate and a front-side insulation layer of saidfirst semiconductor die; an inter-layer dielectric (ILD) layer on saidfront-side of said first semiconductor die, said ILD layer having atleast one contact physically connected to a front-side of said one ormore TSVs and an interface between said at least one contact and saidone or more TSVs, wherein one of the at least one contact comprises afirst contact and a second contact, wherein the first contact and thesecond contact have widths that are smaller than a width of the said oneor more TSVs, wherein the interface comprises a redistribution layer; aninter-metal dielectric (IMD) layer on said ILD layer, said IMD layerhaving at least one bonding pad electrically connected to said at leastone contact; a second semiconductor die connected to said firstsemiconductor die at said at least one bonding pad; and a metallizationlayer on said back-side of said first semiconductor die, wherein saidmetallization layer comprises: at least one back-side dielectric layerover said back-side; and an etch-stop layer over one of said at leastone back-side dielectric layers; said metallization layer having atleast one back-side contact having a first side electrically connectedto a back-side of said one or more TSVs and a second side opposite thefirst side exposed to allow current to flow through the second side. 2.The stacked IC of claim 1, wherein the ILD layer is in direct contactwith a portion of the front-side of said one or more TSVs.
 3. Thestacked IC of claim 1, further comprising a conductive materialextending through the ILD layer to contact the substrate.
 4. The stackedIC of claim 3, wherein the conductive material is in electricalconnection with at least one of the one or more active devices on thesubstrate.
 5. The stacked IC of claim 1, further comprising a lineroxide disposed along sidewalls of the one or more TSVs.
 6. The stackedIC of claim 1, wherein the redistribution layer comprises more than onemetal layer.
 7. A semiconductor device comprising: a semiconductorsubstrate with active devices located on a first side of thesemiconductor substrate; a through substrate via extending from thefirst side of the semiconductor substrate to a second side of thesemiconductor substrate, the second side of the semiconductor substratebeing opposite the first side of the semiconductor substrate; aplurality of first contacts over the first side of the semiconductorsubstrate and in electrical connection with the through substrate via,wherein each one of the plurality of first contacts has a width that isless than a width of the through substrate via, wherein the plurality offirst contacts over the first side of the semiconductor substrate are inelectrical connection with the through substrate via through aredistribution layer; a bond pad over the first side of thesemiconductor substrate and electrically connected to the plurality offirst contacts, wherein a first surface of the bond pad is exposed forelectrical contact; and a second contact located adjacent to the secondside of the semiconductor substrate and electrically connected to thethrough substrate via, wherein a second surface of the second contact isexposed for electrical contact.
 8. The semiconductor device of claim 7,wherein the plurality of first contacts are embedded within a firstdielectric layer which also surrounds at least a portion of the throughsubstrate via.
 9. The semiconductor device of claim 8, furthercomprising a contact extending through the first dielectric layer and inelectrical contact with the semiconductor substrate.
 10. Thesemiconductor device of claim 8, wherein the first dielectric layer isin physical contact with a conductive surface of the through substratevia.
 11. The semiconductor device of claim 10, further comprising asecond semiconductor die bonded to the bond pad.
 12. The semiconductordevice of claim 11, wherein the second semiconductor die comprises athrough substrate via that extends from a first side of a secondsemiconductor substrate to a second side of the semiconductor substrate.13. The semiconductor device of claim 7, further comprising a lineroxide disposed along sidewalls of the through substrate via.
 14. Thesemiconductor device of claim 7, wherein the redistribution layercomprises a plurality of metal layers.
 15. A semiconductor devicecomprising: a first semiconductor die comprising: a first semiconductorsubstrate; a first through substrate via extending from a first side ofthe first semiconductor substrate to a second side of the firstsemiconductor substrate, the first through substrate via having a firstwidth; a first contact in connection with the first through substratevia, the first contact having a second width less than the first width;a second contact in connection with the first through substrate via, thesecond contact having a second width less than the first width; a firstbond pad in electrical connection with both the first contact and thesecond contact; and a dielectric layer, wherein each of the firstthrough substrate via, the first contact, and the second contact extendat least partially into the dielectric layer; and a second semiconductordie bonded to the first semiconductor die, wherein the secondsemiconductor die further comprises: a second semiconductor substrate; asecond bond pad bonded to the first bond pad; and a second throughsubstrate via extending from a first side of the second semiconductorsubstrate to a second side of the second semiconductor substrate,wherein the second through substrate via is in electrical connectionwith the second bond pad.
 16. The semiconductor device of claim 15,wherein the first contact is in direct physical connection with thefirst through substrate via.
 17. The semiconductor device of claim 16,wherein the second contact is in direct physical connection with thefirst through substrate via.
 18. The semiconductor device of claim 15,wherein the dielectric layer is in physical contact with a conductivesurface of the first through substrate via.
 19. The semiconductor deviceof claim 15, wherein the first contact is in connection with the firstthrough substrate via through a redistribution layer.
 20. Thesemiconductor device of claim 19, wherein the redistribution layercomprises more than one metal layer.